Enabling Segment Routing

Basic SR configuration is very simple. In fact, it is easier to enable SR than it is to configure LDP. All you need to do is to allow ‘source-packet-routing’ under protocol IS-IS and specify unique node identifier for each SR-enabled device.

Configure Segment Routing with Node Segment Identifiers

P1

set protocols isis source-packet-routing node-segment ipv4-index 1

P2

set protocols isis source-packet-routing node-segment ipv4-index 2

PE-1

set protocols isis source-packet-routing node-segment ipv4-index 201

PE-2

set protocols isis source-packet-routing node-segment ipv4-index 202

Make sure that Node SIDs and Adjacency SIDs are being advertised and received

Verify Global SID labels

On one of the nodes, verify IS-IS database to make sure that SPRING sub-TLVs have been propagated. MPLS Label for a given Global-SID will be calculated as SID Label Value (800,000) plus Node SID Index.

For example, ipv4-index value 201 was assigned PE-1:

set protocols isis source-packet-routing node-segment ipv4-index 201

This means that global MPLS Label 800,201 can be used to forward traffic to PE-1: